JPH0766239A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the heat radiating characteristics of a semiconductor device, and to prevent generation of stress by thermal expansion. CONSTITUTION:In the semiconductor device in which the surface 21, where the electrodes 22 and 23 of a semiconductor chip 20 are formed, is adhered to a substrate 11 and the wiring conductor layer fixed to the substrate 11 using a conductive bonding agent, an anisotropic conductive bonding agent 40, having conductive particles 42 and the particles of the diameter smaller than the conductive particles 42, is used as the conductive bonding agent. Besides, the thermal expansion coefficient of the substrate 11 is almost equalized to that of the semiconductor chip 20 in the semiconductor device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a semiconductor device having improved heat dissipation characteristics.

[0002]

2. Description of the Related Art An adhesive structure for a semiconductor chip in a conventional semiconductor device is disclosed in JP-A-51-115773. FIG. 4 shows a cross-sectional structure of this conventional example. In FIG. 4, external lead terminals 52a, 52b, 52c are fixed on a hybrid IC substrate 51 that also serves as a heat sink. Electrode pads 62a of the semiconductor chip 60,
The surface 61 on which 62b and 62c are formed is adhered to the external lead terminals 52a, 52b and 52c and the substrate 51 by the anisotropic conductive adhesive 70. Here, the anisotropic conductive adhesive 70 is composed of metal particles 72 in a polymer binder 71.
(Diameter is 10 to 20 μm). In this case, the anisotropic conductive adhesive 70 is applied to the electrode pad 62a.
The external lead terminal 52a, the electrode pad 62b and the external lead terminal 52b, and the electrode pad 62c and the external lead terminal 52c are electrically connected to each other. Due to the nature of the anisotropic conductive adhesive 70, the electrode pads 62a, 62
b, 62c, external lead terminals 52a, 52b, 5
Electrical insulation is secured between 2c and between the electrode pads and the combinations of the external lead terminals other than the above.

[0003]

In the above-mentioned conventional example, the anisotropic conductive adhesive 70 has good electrical characteristics, but the thermal resistance is not sufficiently small. Therefore, the allowable power loss of the semiconductor chip 60 cannot be increased. Further, a temperature rise due to heat generation of the semiconductor chip 60 causes a difference in thermal expansion between the semiconductor chip 60 and the substrate 51, so that stress is generated between the semiconductor chip 60 and the substrate 51, and this stress is applied to the semiconductor device. Caused the deterioration of. Therefore, an object of the present invention is to provide a semiconductor device which eliminates the above-mentioned drawbacks of the conventional example, can well transmit the heat generation of the semiconductor chip to the substrate, and prevents stress due to thermal expansion from occurring. .

[0004]

In order to solve the above-mentioned problems, a first structure of the present invention provides a wiring conductor layer having a surface on which electrodes of a semiconductor chip are formed fixed on a substrate and the substrate. In the semiconductor device adhered with a conductive adhesive, the conductive adhesive is an anisotropic conductive adhesive having conductive particles and heat conductive particles having a diameter smaller than that of the conductive particles. Further, a second configuration is a semiconductor device in which a surface of a semiconductor chip on which electrodes are formed is adhered to a wiring conductor layer fixed on a substrate and the substrate with a conductive adhesive, and the conductive adhesive is used. An anisotropic conductive adhesive having conductive particles and heat conductive particles having a diameter smaller than that of the conductive particles is used, and the coefficient of thermal expansion of the substrate and the coefficient of thermal expansion of the semiconductor chip are made substantially equal.

[0005]

With the first structure, the heat conductive particles in the anisotropic conductive adhesive reduce the thermal resistance of the anisotropic conductive adhesive. In addition, the conductive particles in the anisotropic conductive adhesive make electrical connection between the electrodes of the semiconductor chip and the wiring conductor layer. At this time, since the diameter of the heat conductive particles in the anisotropic conductive adhesive is smaller than the diameter of the conductive particles, the presence of the heat conductive particles means that the conductive particles cause the electrodes of the semiconductor chip and the conductive layer for wiring. Does not interfere with the electrical connection between and. Further, according to the second configuration, the thermally conductive particles in the anisotropic conductive adhesive reduce the thermal resistance of the anisotropic conductive adhesive as in the first configuration described above, and at the same time, the substrate and the semiconductor chip. Since the coefficients of thermal expansion of the semiconductor chips are almost equal to each other, the thermal expansion of the semiconductor chip and the thermal expansion of the substrate due to the heat generation of the semiconductor chip can be almost equal to each other, and this thermal expansion causes stress between the semiconductor chip and the substrate. Can rarely occur.

[0006]

An embodiment of the present invention will be described with reference to the drawings. 1 shows a sectional structure of an embodiment of the present invention, FIG. 2 shows a plane of the embodiment, and FIG. 3 shows an AA sectional structure of FIG. 1 to 3, wiring conductor layers 12a to 12d are fixed on an aluminum nitride (AlN) substrate 11 that also serves as a heat sink. The coefficient of thermal expansion of the aluminum nitride substrate 11 is substantially equal to the coefficient of thermal expansion of the power semiconductor chip 20. Since the power semiconductor chip 20 incorporates a power transistor, an emitter electrode 22, a base electrode 23 and a collector electrode 24 of this power transistor are formed. Of these, the surface 21 on the side where the emitter electrode 22 and the base electrode 23 are formed is bonded to the wiring conductor layers 12b and 12c and the substrate 11 with an anisotropic conductive adhesive 40.
The collector electrode 24 is connected to the wiring conductor layer 12a by the aluminum bonding wire 13.
The surface 31 of the control IC chip 30 on which the electrodes 32, 33, etc. are formed is adhered to the wiring conductor layers 12c, 12d and the substrate 11 by an anisotropic conductive adhesive 40.
The anisotropic conductive adhesive 40 is a mixture of conductive particles 42 and heat conductive particles 43 in a binder 41.
Of these, the diameter of the heat conductive particles 43 is formed smaller than the diameter of the conductive particles 42. Therefore, the conductive particles 4
2 has a diameter of 10 to 20 μm, and the thermally conductive particles 43 have a diameter of 10
It is less than μm. The material of the heat conductive particles 43 is Al
N, and the material of the conductive particles 42 is metal. Furthermore,
The anisotropic conductive adhesive 40 contains more heat conductive particles 43 than the conductive particles 42. The material of the binder 41 is polymer or the like.

With the above structure, in this embodiment, as shown in FIG. 1, the conductive particles 42 are arranged in a row in the lateral direction in the drawing, but since a gap is generated between the conductive particles 42, a difference occurs. The anisotropic conductive adhesive 40 has conductivity in the vertical direction in the drawing, but does not have conductivity in the horizontal direction in the drawing. Further, since the diameter of the heat conductive particles 43 is smaller than the diameter of the conductive particles 42, the heat conductive particles 43 are dispersed so as to enter between the conductive particles 42. Therefore, anisotropy of heat conduction does not occur. In this embodiment, the anisotropic conductive adhesive 40
If there is no anisotropy in heat conduction of the power semiconductor chip 20
The heat generated in the substrate 11 is transferred to the substrate 11 through the anisotropic conductive adhesive 40.
It becomes easy to radiate heat to. In FIG. 1, the anisotropic conductive adhesive 40 is used for the power semiconductor chip 20 of the substrate 11.
Although it is applied to the entire surface of the part corresponding to the lower part of the figure,
The application range of the anisotropic conductive adhesive 40 is the conductor layer 1 for wiring.
Only the portion having 2b and 12c may be used. Also, for control I
Adhesion between the C chip 30 and the substrate 11 also has the same effect as adhesion between the power semiconductor chip 20 and the substrate 11 described above. Furthermore, since the thermal expansion coefficients of the substrate 11 and the power semiconductor chip 20 are made substantially equal, the thermal expansion of the power semiconductor chip 20 and the thermal expansion of the substrate 11 due to the heat generation of the power semiconductor chip 20 can be made substantially equal.
Due to this thermal expansion, stress is hardly generated between the semiconductor chip 20 and the substrate 11. In the above-described embodiment, beryllium oxide (BeO) may be used instead of aluminum nitride (AlN).

[0008]

As described in detail above, according to the semiconductor device of the present invention, a semiconductor using an anisotropic conductive adhesive for bonding the semiconductor chip to the wiring conductor layer on the substrate and the substrate. The heat dissipation characteristics of the device can be significantly improved. Therefore, the allowable power loss of the semiconductor chip can be increased. Further, since the thermal expansion coefficient of the substrate and that of the semiconductor chip are made substantially equal to each other, the stress due to the thermal expansion can be prevented from being generated, so that the deterioration of the semiconductor device due to the stress can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a plan view of an embodiment of the present invention.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view of a conventional example.

[Explanation of symbols]

 11 Substrate 12a-12d Wiring Conductor Layer 20 Power Semiconductor Chip 21 Surface of Power Semiconductor Chip 22 Emitter Electrode 23 Base Electrode 40 Anisotropic Conductive Adhesive 42 Conductive Particle 43 Thermal Conductive Particle

Claims (2)

[Claims] 1. A semiconductor device in which a surface of a semiconductor chip on which an electrode is formed is adhered to a wiring conductor layer fixed on a substrate and a conductive adhesive, and the conductive adhesive is conductive particles. And a semiconductor device comprising an anisotropic conductive adhesive having heat conductive particles having a diameter smaller than that of the conductive particles. 2. A semiconductor device in which a surface of a semiconductor chip on which electrodes are formed is fixed on a substrate by a wiring conductor layer and the substrate is bonded by a conductive adhesive, wherein the conductive adhesive is conductive particles. And an anisotropic conductive adhesive having heat conductive particles having a smaller diameter than the conductive particles,
A semiconductor device, wherein the coefficient of thermal expansion of the substrate and the coefficient of thermal expansion of the semiconductor chip are made substantially equal.